长周期地震动对独塔宽幅斜拉桥地震响应的影响  

Effect of Long-period Ground Motions on Seismic Response of a Cable-stayed Bridge with Single Pylon and Wide Deck

作　　者：魏晓龙[1,2] 徐略勤[1,2] 乔万芝 李钟雄 Wei Xiao-long Xu Lue-qin Qiao Wan-zhi Li Zhong-xiong(School of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074, China State Key Laboratory Breeding Baseof Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, Chongqing 400074, China)

机构地区：[1]重庆交通大学土木工程学院,重庆400074 [2]重庆交通大学山区桥梁与隧道工程国家重点实验室培育基地,重庆400074

出　　处：《工程抗震与加固改造》2017年第4期92-100,152,共10页Earthquake Resistant Engineering and Retrofitting

基　　金：重庆市基础与前沿研究计划项目(cstc2015jcyj A30014);国家自然科学基金资助项目(51408089)

摘　　要：为了预测独塔宽幅斜拉桥长周期地震响应,以便进行更合理的抗震设计和评估,采用Open SEES软件建立了某独塔宽幅斜拉桥的非线性有限元模型,基于傅里叶变换分析了长周期地震动频谱特性,对比研究了桥梁在远场谐和型地震波、近断层脉冲型地震波、普通地震波以及与设计反应谱匹配的人工地震波作用下的动力响应,并基于能力/需求法对该桥的抗震性能进行了评估。研究表明:长周期地震动对周期为2~4s的独塔宽幅斜拉桥的地震响应具有明显的放大作用,远场谐和型地震波作用下的内力响应为普通地震波的2倍以上,位移响应为普通地震波的18倍以上;主塔塔底截面抗震性能是全桥抗震性能的关键环节,长周期地震动会使塔底截面产生显著的塑性变形,导致主塔和主梁产生大位移,并引发支座破坏;背景工程的横桥向抗震性能比纵桥向更低,且长周期地震动对横桥向抗震性能的影响更明显。In order to predict the seismic response of cable-stayed bridges with single pylon and wide deck for seismic design and evaluation, the software of Open SEES is applied to establish a nonlinear finite element model for the background bridge. The characteristics of frequency contents are analyzed for the long-period ground motions based on the Fourier transformation method. The dynamic response of the background bridge is compared under the four types of ground motions, i.e. the far-fauh harmonic type, the near-fauh type and near fault slip type, ordinary ground motions and the artificial ground motions which are compatible with the code spectrum. The seismic performance of the bridge is evaluated using the capacity/demand ratio method. The results show that the long- period ground motions will significantly amplify the seismic response of cable-stayed bridges with the fundamental vibration period of 2 - 4s. The force response of the bridge under the far-fauh harmonic type ground motion ise over two times larger than that of the bridge under the ordinary ground motions, and the displacement response is more than 18 times greater than that under the ordinary ground motion. The pylon is the critical element of the whole bridge when exposes to intensive earthquakes, and the long-period ground motions will produce remarkable plastic deformation in the pylon base section which in return leads to large displacement response at the pylon top as well as in the girder and causes damage of bearings. It is found that the seismic performance of the background bridge is weaker in transverse direction and the effect of long-period ground motion on the seismic performance of the bridge is much more pronounced in the transverse direction.

关 键 词：桥梁工程 长周期地震动 独塔宽幅斜拉桥 地震响应 能力/需求 抗震性能 

分 类 号：U442.55[建筑科学—桥梁与隧道工程]